The present invention is directed to materials and methods involving extracellular matrix signalling moleculesxe2x80x94polypeptides involved in cellular responses to growth factors. More particularly, the invention is directed to Cyr61-, Fisp12-, and CTGF-related polynucleotides, polypeptides, compositions thereof, methods of purifying these polypeptides, and methods of using these polypeptides.
The growth of mammalian cells is tightly regulated by polypeptide growth factors. In the adult animal, most cells are metabolically active but are quiescent with regard to cell division. Under certain conditions, these cells can be stimulated to reenter the cell cycle and divide. As quiescent cells reenter the active growth and division phases of the cell cycle, a number of specific genes, the immediate early genes, are rapidly activated. Reentry to the active cell cycle is by necessity tightly regulated, since a breakdown of this control can result in uncontrolled growth, frequently recognized as cancer. Controlled reentry of particular cells into the growth phase is essential for such biological processes as angiogenesis (e.g., blood vessel growth and repair), chondrogenesis (e.g., skeletal development and prosthesis integration), oncogenesis (e.g., cancer cell metastasis and tumor neovascularization), and other growth-requiring processes.
Angiogenesis, the formation of new blood vessels from the endothelial cells of preexisting blood vessels, is a complex process which involves a changing profile of endothelial cell gene expression, associated with cell migration, proliferation, and differentiation. Angiogenesis begins with localized breakdown of the basement membrane of the parent vessel. In vivo, basement membranes (primarily composed of laminin, collagen type IV, nidogen/entactin, and proteoglycan) support the endothelial cells and provide a barrier separating these cells from the underlying stroma. The basement membrane also affects a variety of biological activities including cell adhesion, migration, and growth during development and differentiation.
Following breakdown of the basement membrane, endothelial cells migrate away from the parent vessel into the interstitial extracellular matrix (ECM), at least partially due to chemoattractant gradients. The migrating endothelial cells form a capillary sprout, which elongates. This elongation is the result of migration and proliferation of cells in the sprout. Cells located in the leading capillary tip migrate toward the angiogenic stimulus, but neither synthesize DNA nor divide. Meanwhile, behind these leading tip cells, other endothelial cells undergo rapid proliferation to ensure an adequate supply of endothelial cells for formation of the new vessel. Capillary sprouts then branch at their tips, the branches anastomose or join with one another to form a lumen, the basement membrane is reconstituted, and a vascular connection is established leading to blood flow.
Alterations in at least three endothelial cell functions occur during angiogenesis: 1) modulations of interactions with the ECM, which require alterations of cell-matrix contacts and the production of matrix-degrading proteolytic enzymes; 2) an initial increase and subsequent decrease in endothelial cell migration, effecting cell translocation towards an angiogenic stimulus; and 3) a transient increase in cell proliferation, providing cells for the growing and elongating vessel, with a subsequent return to the quiescent cell state once the vessel is formed. These three functions are realized by adhesive, chemotactic, and mitogenic interactions or responses, respectively. Therefore, control of angiogenesis requires intervention in three distinct cellular activities: 1) cell adhesion, 2) cell migration, and 3) cell proliferation. Another biological process involving a similar complex array of cellular activities is chondrogenesis.
Chondrogenesis is the cellular process responsible for skeletal organization, including the development of bone and cartilage. Chondrogenesis, like angiogenesis, involves the controlled reentry of quiescent cells into the growth phase of the cell cycle. The growth phase transition is associated with altered cell adhesion characteristics, changed patterns of cell migration, and transiently increased cell proliferation. Chondrogenesis involves the initial development of chondrogenic capacity (i.e., the proto-differentiated state) by primitive undifferentiated mesenchyme cells. This stage involves the production of chondrocyte-specific markers without the ability to produce a typical cartilage ECM. Subsequently, the cells develop the capacity to produce a cartilage-specific ECM as they differentiate into chondrocytes. Langille, Microscop. Res. and Tech. 28:455-469 (1994). Chondrocyte migration, adhesion, and proliferation then contribute to the development of bony, and cartilaginous, skeleton. Abnormal elaboration of the programmed development of cells participating in the process of chondrogenesis results in skeletal defects presenting problems that range from cosmetic concerns to life-threatening disorders.
Like angiogenesis and chondrogenesis, oncogenesis is characterized by changes in cell adhesion, migration, and proliferation. Metastasizing cancer cells exhibit altered adhesion and migration properties. Establishment of tumorous masses requires increased cell proliferation and the elaboration of the cellular properties characteristic of angiogenesis during the neovascularization of tumors.
Abnormal progression of angiogenesis or chondrogenesis, as well as mere progression of oncogenesis, substantially impairs the quality of life for afflicted individuals and adds to modern health care costs. The features common to these complex biological processes, comprising altered cell adhesion, migration, and proliferation, suggest that agents capable of influencing all three of these cellular activities would be effective in screening for, and modulating, the aforementioned complex biological processes. Although the art is aware of agents that influence individual cellular activities, e.g., integrins and selectins (cell adhesion), chemokines (cell migration), and a variety of growth factors or cytokines (cell proliferation), until recently no agent has been identified that exerts an influence over all three cellular activities in humans.
Murine Cyr61 (CYsteine-Rich protein) is a protein expressed in actively growing and dividing cells that may influence each of these three cellular activities. RNase protection analyses have shown that the gene encoding murine Cyr61, murine cyr61, is transcribed in the developing mouse embryo. O""Brien et al., Cell Growth and Diff. 3:645-654 (1992). In situ hybridization analysis showed that expression of cyr61 during mouse embryogenesis is closely correlated with the differentiation of mesenchymal cells, derived from ectoderm and mesoderm, into chondrocytes. In addition, cyr61 is expressed in the vessel walls of the developing circulatory system. These observations indicate that murine cyr61 is expressed during cell proliferation and differentiation, which are characteristics of expression of genes involved in regulatory cascades that control the cell growth cycle.
Further characterization of the Cyr61 polypeptide has been hampered by an inability to purify useful quantities of the protein. Efforts to purify Cyr61 in quantity by overexpression from either eukaryotic or prokaryotic cells typically fail. Yang, University of Illinois at Chicago, Ph.D. Thesis (1993). One problem associated with attempting to obtain useful quantities of Cyr61 is the reduction in mammalian growth rates induced by overexpression of Cyr61. Another problem with Cyr61 purification is that the cysteine-rich polypeptide, when expressed in bacterial cells using recombinant DNA techniques, is often found in insoluble protein masses. Nevertheless. Cyr61 has been characterized as a polypeptide of 349 amino acids, containing 39 cysteine residues, a hydrophobic putative N-terminal signal sequence, and potential N-linked glycosylation sites (Asn28 and Asn225). U.S. Pat. No. 5,408,040 at column 3, lines 41-54, Grotendorst et al., incorporated herein by reference (the ""040 Patent).
Recently, proteins related to Cyr61 have been characterized. For example, a human protein, Connective Tissue Growth Factor (CTGF), has been identified. (See ""040 Patent). CTGF is expressed in actively growing cells such as fibroblasts and endothelial cells (""040 Patent, at column 5, lines 62-64), an expression pattern shared by Cyr61. In terms of function, CTGF has been described as a protein growth factor because its primary biological activity has been alleged to be its mitogenicity (""040 Patent, at column 2, lines 25-27 and 53-55). In addition, CTGF reportedly exhibits chemotactic activity. ""040 Patent, at column 2, lines 56-59. In terms of structure, the polynucleotide sequence encoding CTGF, and the amino acid sequence of CTGF, have been published. ""040 Patent, SEQ ID NO:7 and SEQ ID NO:8, respectively.
Another apparently related protein is the mouse protein Fisp12 (FIbroblast Secreted Protein). Fisp12 has been subjected to amino acid sequence analysis, revealing a primary structure that is rich in cysteines. Ryseck et al., Cell Growth and Diff. 2:225-233 (1991), incorporated herein by reference. The protein also possesses a hydrophobic N-terminal sequence suggestive of the signal sequence characteristic of secreted proteins.
Sequence analyses involving Cyr61, Fisp12, CTGF, and other proteins, have contributed to the identification of a family of cysteine-rich secreted proteins. Members of the family share similar primary structures encoded by genes exhibiting similar sequences. Each of the proteins in this emerging family is further characterized by the presence of a hydrophobic N-terminal signal sequence and 38 cysteine residues in the secreted forms of the proteins. Members of the family identified to date include the aforementioned Cyr61 (human and mouse), Fisp12 (mouse), and CTGF (the human ortholog of Fisp12), as well as CEF10 (chicken), and Nov (avian).
One of several applications for a purified protein able to affect cell adhesion, migration, and proliferation properties involves the development of stable, long term ex vivo hematopoietic stem cell cultures. Patients subjected to high-dose chemotherapy have suppressed hematopoiesis; expansion of stem cells, their maturation into various hematopoietic lineages, and mobilization of mature cells into circulating blood routinely take many weeks to complete. For such patients, and others who need hematopoietic cell transplantation, introduction into those patients of autologous stem cells that have been manipulated and expanded in culture is advantageous. Such hermatopoietic stem cells (HSC) express the CD34 stem cell antigen, but do not express lineage commitment antigens. These cells can eventually give rise to all blood cell lineages (e.g., erythrocytes, lymphocytes, and myelocytes).
Hematopoietic progenitor cells that can initiate and sustain long term cultures (i.e., long term culture system-initiating cells or LTC-IC) represent a primitive population of stem cells. The frequency of LTC-IC has been estimated at only 1-2 per 104 cells in normal human marrow and only about 1 per 50-100 cells in a highly purified CD34+ subpopulation. Thus, it would be useful to have methods and systems for long term cell culture that maintain and expand primitive, pluripotent human HSC to be used for repopulation of the hematopoietic system in vivo.
Cell culture models of hematopoiesis have revealed a multitude of cytokines that appear to play a role in the hematopoietic process, including various colony stimulating factors, interleukins, stem cell factor, and the c-kit ligand. However, in ex vivo cultures, different combinations of these cytokines favor expansion of different sets of committed progenitors. For example, a factor in cord blood plasma enhanced expansion of granulocyte-erythroid-macrophage-megakaryocyte colony forming unit (CFU-GEMM) progenitors, but expansion in these cultures favored the more mature subsets of cells. Therefore, it has been difficult to establish a culture system that mimics in vivo hematopoiesis.
An HSC culture system should maintain and expand a large number of multi- or pluripotent stem cells capable of both long term repopulation and eventual lineage commitment under appropriate induction. However, in most ex vivo culture systems, the fraction of the cell population comprised of LTC-IC decreases steadily with continued culturing, often declining to 20% of their initial level after several weeks, as the culture becomes populated by more mature subsets of hematopoietic progenitor cells that are no longer pluripotent. Moreover, the proliferative capacity exhibited by individual LTC-IC may vary extensively. Thus, a need exists in the art for HSC culture systems comprising biological agents that maintain or promote the pluripotent potential of cells such as LTC-IC cells. In addition to a role in developing ex vivo HSC cultures, biological agents affecting cell adhesion, migration, and proliferation are useful in a variety of other contexts.
Proteins that potentiate the activity of mitogens but have no mitogenic activity themselves may play important roles as signalling molecules in such processes as hematopoiesis. Moreover, these signalling proteins could also serve as probes in the search for additional mitogens, many of which have not been identified or characterized. Several biological factors have been shown to potentiate the mitogenic activity of other factors, without being mitogenic themselves. Some of these potentiators are associated with the cell surface and/or extracellular matrix. Included in this group are a secreted basic Fibroblast Growth Factor-binding protein (bFGF-binding protein), the basal lamina protein perlecan, and the Human Immunodeficiency Virus-1 TAT protein, each protein being able to promote bFGF-induced cell proliferation and angiogenesis. Also included in this group of mitogen potentiators are thrombospondin, capable of activating a latent form of Transforming Growth Factor-xcex2, and an unidentified secreted growth-potentiating factor from vascular smooth muscle cells (Nakano et al., J. Biol. Chem. 270:5702-5705 [1995]), the latter factor being required for efficient activation of Epidermal Growth Factor- or thrombin-induced DNA synthesis. Further, the B cell stimulatory factor-1/interleukin-4, a T cell product with no demonstrable mitogenic activity, is able to 1) enhance the proliferative response of granulocyte-macrophage progenitors to granulocyte-colony stimulating factor, 2) enhance the proliferative response of erythroid progenitors to erythropoietin, and 3) together with erythropoietin, induce colony formation by multipotent progenitor cells. Similarly, interleukin-7 enhanced stem cell factor-induced colony formation by primitive murine bone marrow progenitors, although interleukin-7 had no proliferative effect by itself. In addition, lymphocyte growth enhancing factor (LGEF) was found to enhance mitogen-stimulated human peripheral blood lymphocyte (PBL) or purified T cell proliferation in a dose-dependent fashion. LGEF alone did not stimulate PBL or T cell proliferation.
Therefore, a need continues to exist for biological agents capable of exerting a concerted and coordinated influence on one or more of the particularized functions collectively characterizing such complex biological processes as angiogenesis, chondrogenesis, and oncogenesis. In addition, a need persists in the art for agents contributing to the reproduction of these in vivo processes in an ex vivo environment, e.g., the development of HSC cultures. Further, there continues to be a need for tools to search for the remaining biological components of these complex processes, e.g., mitogen probes, the absence of which impedes efforts to advantageously modulate and thereby control such processes.
The present invention provides extracellular matrix (ECM) signalling molecule-related materials and methods. In particular, the present invention is directed to polynucleotides encoding ECM signalling molecules and fragments or analogs thereof, ECM signalling molecule-related polypeptides and fragments, analogs, and derivatives thereof, methods of producing ECM signalling molecules, and methods of using ECM signalling molecules.
One aspect of the present invention relates to a purified and isolated polypeptide comprising an ECM signalling molecule. The polypeptides according to the invention retain at least one biological activity of an ECM signalling molecule, such as the ability to stimulate cell adhesion, cell migration, or cell proliferation; the ability to modulate angiogenesis, chondrogenesis, or oncogenesis; immunogenicity or the ability to elicit an immune response; and the ability to bind to polypeptides having specific binding sites for ECM signalling molecules, including antibodies and integrins. The polypeptides may be native or recombinant molecules. Further, the invention comprehends full-length ECM signalling molecules, and fragments thereof. In addition, the polypeptides of the invention may be underivatized, or derivatized in conformity with a native or non-native derivatization pattern. The invention further extends to polypeptides having a native or naturally occurring amino acid sequence, and variants (i.e., polypeptides having different amino acid sequences), analogs (i.e., polypeptides having a non-standard amino acid or other structural variation from the conventional set of amino acids) and homologs (i.e., polypeptides sharing a common evolutionary ancestor with another polypeptide) thereof. Polypeptides that are covalently linked to other compounds, such as polyethylene glycol, or other proteins or peptides, i.e. fusion proteins, are contemplated by the invention.
Exemplary ECM signalling molecules include mammalian Cyr61, Fisp12, and CTGF polypeptides. Beyond ECM signalling molecules, the invention includes polypeptides that specifically bind an ECM signalling molecule of the invention, such as the aforementioned antibody products. A wide variety of antibody products fall within the scope of the invention, including polyclonal and monoclonal antibodies, antibody fragments, chimeric antibodies, CDR-grafted antibodies, xe2x80x9chumanizedxe2x80x9d antibodies, and other antibody forms known in the art. Other molecules such as peptides, carbohydrates or lipids designed to bind to an active site of the ECM molecules thereby inhibiting their activities are also contemplated by the invention. However molecules such as peptides that enhance or potentiate the activities of ECM molecule are also within the scope of the invention. The invention further extends to a pharmaceutical composition comprising a biologically effective amount of a polypeptide and a pharmaceutically acceptable adjuvant, diluent or carrier, according to the invention. A xe2x80x9cbiologically effective amountxe2x80x9d of the biomaterial is an amount that is sufficient to result in a detectable response in the biological sample when compared to a control lacking the biomaterial.
Another aspect of the invention relates to a purified and isolated polynucleotide comprising a sequence that encodes a polypeptide of the invention. A polynucleotide according to the invention may be DNA or RNA, single- or double-stranded, and may be may purified and isolated from a native source, or produced using synthetic or recombinant techniques known in the art. The invention also extends to polynucleotides encoding fragments, analogs (i.e., polynucleotides having a non-standard nucleotide), homologs (i.e., polynucleotides having a common evolutionary ancestor with another polynucleotide), variants (i.e., polynucleotides differing in nucleotide sequence), and derivatives (i.e., polynucleotides differing in a structural manner that does not involve the primary nucleotide sequence) of ECM molecules. Vectors comprising a polynucleotide according to the invention are also contemplated. In addition, the invention comprehends host cells transformed or transfected with a polynucleotide or vector of the invention.
Other aspects of the invention relate to methods for making or using the polypeptides and/or polynucleotides of the invention. A method for making a polypeptide according to the invention comprises expressing a polynucleotide encoding a polypeptide according to the present invention in a suitable host cell and purifying the polypeptide. Other methods for making a polypeptide of the invention use techniques that are known in the art, such as the isolation and purification of native polypeptides or the use of synthetic techniques for polypeptide production. In particular, a method of purifying an ECM signalling molecule such as human Cyr61 comprises the steps of identifying a source containing human Cyr61, exposing the source to a human Cyr61-specific biomolecule that binds Cyr61 such as an anti-human Cyr61 antibody, and eluting the human Cyr61 from the antibody or other biomolecule, thereby purifying the human Cyr61.
Another aspect of the invention is a method of screening for a modulator of angiogenesis comprising the steps of: (a) contacting a first biological sample capable of undergoing angiogenesis with a biologically effective (i.e., angiogenically effective) amount of an ECM signalling molecule-related biomaterial and a suspected modulator (inhibitor or potentiator); (b) separately contacting a second biological sample with a biologically effective amount of an ECM signalling molecule-related biomaterial, thereby providing a control; (c) measuring the level of angiogenesis resulting from step (a) and from step (b); and (d) comparing the levels of angiogenesis measured in step (c), whereby a modulator of angiogenesis is identified by its ability to alter the level of angiogenesis when compared to the control of step (b). The modulator may be either a potentiator or inhibitor of angiogenesis and the ECM signalling molecule-related biomaterial includes, but is not limited to, Cyr61, and fragments, variants, homologs, analogs, derivatives, and antibodies thereof.
The invention also extends to a method of screening for a modulator of angiogenesis comprising the steps of: (a) preparing a first implant comprising Cyr61 and a second implant comprising Cyr61 and a suspected modulator of Cyr61 angiogenesis; (b) implanting the first implant in a first cornea of a test animal and the second implant in a second cornea of the test animal; (c) measuring the development of blood vessels in the first and second corneas; and (d) comparing the levels of blood vessel development measured in step (c), whereby a modulator of angiogenesis is identified by its ability to alter the level of blood vessel development in the first cornea when compared to the blood vessel development in the second cornea.
Another aspect of the invention relates to a method of screening for a modulator of chondrogenesis comprising the steps of: (a) contacting a first biological sample capable of undergoing chondrogenesis with a biologically effective (e.g. chondrogenically effective) amount of an ECM signalling molecule-related biomaterial and a suspected modulator; (b) separately contacting a second biological sample capable of undergoing chondrogenesis with a biologically effective amount of an ECM signalling molecule-related biomaterial, thereby providing a control; (c) measuring the level of chondrogenesis resulting from step (a) and from step (b); and (d) comparing the levels of chondrogenesis measured in step (c), whereby a modulator of chondrogenesis is identified by its ability to alter the level of chondrogenesis when compared to the control of step (b). The modulator may be either a promoter or an inhibitor of chondrogenesis; the ECM signalling molecules include those defined above and compounds such as mannose-6-phosphate, heparin, and tenascin.
The invention also relates to an in vitro method of screening for a modulator of oncogenesis comprising the steps of: (a) inducing a first tumor and a second tumor; (b) administering a biologically effective amount of an ECM signalling molecule-related biomaterial and a suspected modulator to the first tumor; (c) separately administering a biologically effective amount of an ECM signalling molecule-related biomaterial to the second tumor, thereby providing a control; (d) measuring the level of oncogenesis resulting from step (b) and from step (c); and (e) comparing the levels of oncogenesis measured in step (d), whereby a modulator of oncogenesis is identified by its ability to alter the level of oncogenesis when compared to the control of step (c). Modulators of oncogenesis contemplated by the invention include inhibitors of oncogenesis. Tumors may be induced by a variety of techniques including, but not limited to, the administration of chemicals, e.g., carcinogens, and the implantation of cancer cells. A related aspect of the invention is a method for treating a solid tumor comprising the step of delivering a therapeutically effective amount of a Cyr61 inhibitor to an individual, thereby inhibiting the neovascularization of the tumor. Inhibitors include, but are not limited to, inhibitor peptides such as peptides having the xe2x80x9cRGDxe2x80x9d motif, and cytotoxins, which may be free or attached to molecules such as Cyr61.
Yet another aspect of the invention is directed to a method of screening for a modulator of cell adhesion comprising the steps of: (a) preparing a surface compatible with cell adherence; (b) separately placing first and second biological samples capable of undergoing cell adhesion on the surface; (c) contacting a first biological sample with a suspected modulator and a biologically effective amount of an ECM signalling molecule-related biomaterial selected from the group consisting of a human Cyr61, a human Cyr61 fragment, a human Cyr61 analog, and a human Cyr61 derivative; (d) separately contacting a second biological sample with a biologically effective amount of an ECM signalling molecule-related biomaterial selected from the group consisting of a human Cyr61, a human Cyr61 fragment, a human Cyr61 analog, and a human Cyr61 derivative, thereby providing a control; (e) measuring the level of cell adhesion resulting from step (c) and from step (d); and (f) comparing the levels of cell adhesion measured in step (e), whereby a modulator of cell adhesion is identified by its ability to alter the level of cell adhesion when compared to the control of step (d).
The invention also extends to a method of screening for a modulator of cell migration comprising the steps of: (a) forming a gel matrix comprising Cyr61 and a suspected modulator of cell migration; (b) preparing a control gel matrix comprising Cyr61; (c) seeding endothelial cells capable of undergoing cell migration onto the gel matrix of step (a) and the control gel matrix of step (b); (d) incubating the endothelial cells; (e) measuring the levels of cell migration by inspecting the interior of the gel matrix and the control gel matrix for cells; (f) comparing the levels of cell migration measured in step (e), whereby a modulator of cell migration is identified by its ability to alter the level of cell migration in the gel matrix when compared to the level of cell migration in the control gel matrix. The endothelial cells include, but are not limited to, human cells, e.g., human microvascular endothelial cells. The matrix may be formed from gelling materials such as Matrigel, collagen, or fibrin or combinations thereof.
Another aspect of the invention is directed to an in vitro method of screening for cell migration comprising the steps of: (a) forming a first gelatinized filter and a second gelatinized filter, each filter having two sides; (b) contacting a first side of each the filter with endothelial cells, thereby adhering the cells to each the filter; (c) applying an ECM signalling molecule and a suspected modulator of cell migration to a second side of the first gelatinized filter and an ECM signalling molecule to a second side of the second gelatinized filter; (d) incubating each the filter; (e) detecting cells on the second side of each the filter, and (f) comparing the presence of cells on the second side of the first gelatinized filter with the presence of cells on the second side of the second gelatinized filter, whereby a modulator of cell migration is identified by its ability to alter the level of cell migration measured on the first gelatinized filter when compared to the cell migration measured on the second gelatinized filter. The endothelial cells are defined above. The ECM signalling molecules extend to human Cyr61 and each of the filters may be placed in apparatus such as a Boyden chamber, including modified Boyden chambers.
The invention also embraces an in vivo method of screening for a modulator of cell migration comprising the steps of: (a) removing a first central portion of a first biocompatible sponge and a second central portion of a second biocompatible sponge; (b) applying an ECM signalling molecule and a suspected modulator to the first central portion and an ECM signalling molecule to the second central portion; (c) reassociating the first central portion with said first biocompatible sponge and said second central portion with the second biocompatible sponge; (d) attaching a first filter to a first side of the first biocompatible sponge and a second filter to a second side of the first biocompatible sponge; (e) attaching a third filter to a first side of the second biocompatible sponge and a fourth filter to a second side of the second biocompatible sponge; (f) implanting each of the biocompatible sponges, each biocompatible sponge comprising the central portion and the filters, in a test animal; (e) removing each the sponge following a period of incubation; (f) measuring the cells found within each of the biocompatible sponges; and (g) comparing the presence of cells in the first biocompatible sponge with the presence of cells in the second biocompatible sponge, whereby a modulator of cell migration is identified by its ability to alter the level of cell migration measured using the first biocompatible sponge when compared to the cell migration measured using the second biocompatible sponge. ECM signalling molecules include, but are not limited to, human Cyr61; the ECM signalling molecule may also be associated with Hydron. In addition, the in vivo method of screening for a modulator of cell migration may include the step of providing a radiolabel to the test animal and detecting the radiolabel in one or more of the sponges.
Another aspect of the invention relates to a method for modulating hemostasis comprising the step of administering an ECM signalling molecule in a pharmaceutically acceptable adjuvant, diluent or carrier. Also, the invention extends to a method of inducing wound healing in a tissue comprising the step of contacting a wounded tissue with a biologically effective amount of an ECM signalling molecule, thereby promoting wound healing. The ECM signalling molecule may be provided in the form of an ECM signalling molecule polypeptide or an ECM signalling molecule nucleic acid, e.g., using a gene therapy technique. For example. the nucleic acid may comprise an expression control sequence operably linked to an ECM signalling molecule which is then introduced into the cells of a wounded tissue. The expression of the coding sequence is controlled, e.g., by using a tissue-specific promoter such as the K14 promoter operative in skin tissue to effect the controlled induction of wound healing. The nucleic acid may include a vector such as a Herpesvirus, an Adenovirus, an Adeno-associated Virus, a Cytomegalovirus, a Baculovirus, a retrovirus, and a Vaccinia Virus. Suitable wounded tissues for treatment by this method include, but are not limited to, skin tissue and lung epithelium. A related method comprises administering a biologically effective amount of an ECM signalling molecule, e.g. Cyr61, to an animal to promote organ regeneration. The impaired organ may be the result of trauma, e.g. surgery, or disease. Another method of the invention relates to improving the vascularization of grafts, e.g., skin grafts. Another method of the invention is directed to a process for promoting bone implantation, including bone grafts. The method for promoting bone implantation comprises the step of contacting a bone implant or receptive site with a biologically effective (i.e., chondrogenically effective) amount of an ECM signalling molecule. The contacting step may be effected by applying the ECM signalling molecule to a biocompatible wrap such as a biodegradable gauze and contacting the wrap with a bone implant, thereby promoting bone implantation. The bone implants comprise natural bones and fragments thereof, as well as inanimate natural and synthetic materials that are biocompatible, such as prostheses. In addition to direct application of an ECM signalling molecule to a bone, prosthesis, or receptive site, the invention contemplates the use of matrix materials for controlled release of the ECM signalling molecule, in addition to such application materials as gauzes.
Yet another aspect of the invention relates to a method of screening for a modulator of cell proliferation comprising the steps of: (a) contacting a first biological sample capable of undergoing cell proliferation with a suspected modulator and a biologically effective (i.e., mitogenically effective) amount of an ECM signalling molecule-related biomaterial selected from the group consisting of a human Cyr61, a human Cyr61 fragment, a human Cyr61 analog, and a human Cyr61 derivative; (b) separately contacting a second biological sample capable of undergoing cell proliferation with a biologically effective amount of an ECM signalling molecule-related biomaterial selected from the group consisting of a human Cyr61, a human Cyr61 fragment, a human Cyr61 analog, and a human Cyr61 derivative, thereby providing a control; (c) incubating the first and second biological samples; (d) measuring the level of cell proliferation resulting from step (c); and (e) comparing the levels of cell proliferation measured in step (d), whereby a modulator of cell proliferation is identified by its ability to alter the level of cell adhesion when compared to the control of step (b).
Also comprehended by the invention is a method for expanding a population of undifferentiated hematopoietic stem cells in culture, comprising the steps of: (a) obtaining hermatopoietic stem cells from a donor; and (b) culturing said cells tinder suitable nutrient conditions in the presence of a biologically effective (i.e., hematopoietically effective) amount of Cyr61.
Another method according to the invention is a method of screening for a mitogen comprising the steps of: (a) plating cells capable of undergoing cell proliferation; (b) contacting a first portion of the cells with a solution comprising Cyr61 and a suspected mitogen; (c) contacting a second portion of the cells with a solution comprising Cyr61, thereby providing a control; (c) incubating the cells; (d) detecting the growth of the first portion of cells and the second portion of the cells; and (e) comparing growth of the first and second portions of cells, whereby a mitogen is identified by its ability to induce greater growth in the first portion of cells when compared to the growth of the second portion of cells. The cells include, but are not limited to, endothelial cells and fibroblast cells. Further, the method may involve contacting the cells with a nucleic acid label, e.g., [3H]-thymidine, and detecting the presence of the label in the cells. Another method relates to improving tissue grafting, comprising administering to an animal a quantity of Cyr61 effective in improving the rate of neovascularization of a graft.
Numerous additional aspects and advantages of the present invention will be apparent upon consideration of the following drawing and detailed description.